Joule Thief

[NickZ]

   Gary:
   Thanks for the great idea on the feed-back, I'll try that one soon. I've heard about it, but have not tried it yet. I think that I have everything I need on hand.  If I can get it to work, maybe it can be upgraded, also.
  I intend to make a kind of Joule Thief-TPU.  But I have been wondering if anyone ever tried to make a one or two foot bifilar toroid air core coil connected to a strong 12 volt Jtc? One that can light a CFL?   I think that it should work kick ass...  But, has it been done?   Yes,  No?
 
   I have tried a few different big Jtc using different methods, like switching run and charge batteries back and forth, but there is always a loss that eventually means that the device will run down, and a bump-charge is necessary to keep it up.

  The problem with self running has always been that the frequency changes when using the small AA batteries. And as they get discharged, the jtc looses resonance and quickly loses any of the special effects.  So, I think that a small solar panel and 12 volt battery are the way to go, to avoid that problem, and maintain the device in resonance.
12 volts sounds interesting. Maybe for now I can use a 12 volt 500 mA wall adapter and resistor, if needed, to give it a try.
   Gary, thanks again for the ideas...
             

[dasimpson]

Dasimpson

What kind of battery will you be using?

My design is for a JT type charger...... the transistor controls the circuit indirectly.....so  a large transistor should not be needed.

With a large transistor or mosfet you could run the power charging the battery directly through the transistor........controlling it directly



gary

only small 1.2 or 2.4 volt from 3 solar cells that put out about 40 ma total cheap garden light ones lol

[dasimpson]

i was thinking something like this i know as it is in the drawing will turn the transistor on at set zenerdiode voltage but i wont it to turn off
here is what i have but dont know how to reverse it to turn off instead plus i think on that image the + and - rail need swopping

[crowclaw]

i was thinking something like this i know as it is in the drawing will turn the transistor on at set zenerdiode voltage but i wont it to turn off
here is what i have but dont know how to reverse it to turn off instead plus i think on that image the + and - rail need swopping

Regarding polarity your drawing is ok. However to set the zener action and provide base bias for your circuit you will need to connect a resistor between the base  of the transistor and the cathode of D1... say around 1K if you reduce this value you increase the base current.

[dasimpson]

i have seen that on other explaernations but couldent make sence of it
could you explain what limiting the current would do
what i wont to happern is when the battery hits the charged voltage i wont the supply voltage to shut off and come on again when they batterys drops below the set level

i thoght the zener would of been on the positive rail so the voltage/current build up until it reaches the overflow point if you get what i mean that then saturated the transistor that then shuts off the flow of power